1. Field of the Invention
This specification relates to an antenna apparatus for transmission or reception of a wireless signal.
2. Background of the Invention
As mobile communication technologies are developed and consumers demand on more various types of services, mobile communication services have continued to evolve. The initial mobile communication has been provided, simply focusing on voice (audio) communication. However, in recent time, various mobile communication services, such as multimedia services like music or movies, wireless portable Internet capable of using the Internet at ultra high speed during travel and satellite communication services for providing mobile communication over borders are appearing.
In the meantime, as an antenna of a general mobile communication terminal is reduced in size, radiation efficiency of the antenna is lowered, a frequency band is narrowed and an antenna gain is reduced. However, size reduction, multi-functionality and high performance are continuously requested for the mobile terminal, in spite of the performance degradation. This also requires for size reduction and high performance with respect to an antenna used for a mobile communication system.
Also, as an interest in a design of a terminal increases and the terminal becomes small and light, a problem that the performance of an internal antenna is lowered as compared to an external antenna is caused. Thus, the mobile terminal is equipped with a main antenna for transmission and reception, which is installed in the terminal for improvement of performance and smooth data communication, and a separate diversity antenna for preventing a fading effect.
The diversity antenna has been developed to an antenna which can be easily installed even in a narrow space within a terminal body. Examples of the diversity antenna include a Planar Inverted F-Antenna (PIFA) having a sufficient distance more than λ/2 from the main antenna, a meander antenna having a curved pattern, a loop antenna, an inverted F-antenna, a wire type antenna and the like.
For use of the conventional external antenna, lowering of antenna performance is not exhibited by virtue of a sufficiently spaced distance from the diversity antenna. However, for use of an internal main antenna which occupies more than a predetermined area of an inner space of the terminal, an isolation less than 5 dB is acquired due to an insufficiently space distance from the diversity antenna, causing the performance of the main antenna to be lowered due to interference with each other.
Further, with the development of communication technologies applied to mobile terminals, terminals supporting a dual mode or triple mode in addition to the conventional single frequency transmission and reception function are released, and various types of applications, such as CDMA, PCS, WCDMA, GSM, GPS, WIFI, Bluetooth, Long Term Evolution (LTE), Wimax functions are implemented in one terminal. Also, the size reduction of the terminal results in installing many antennas within a narrow space.
Terminals employing diversity antennas with different frequency bands cause difficulty in ensuring an installation space and a spaced distance for the diversity antennas, and the problem caused due to the interference between the antennas becomes worse.
Consequently, an antenna apparatus which is capable of ensuring installation space and spaced distance and achieving higher efficiency may be taken into account.